The invention relates to electrical machines, in particular to the design of machine components with ferromagnetic materials and in particular measures for guiding the magnetic flux.
Electrical machines generally have stators with stator teeth. Stator coils which generate a magnetic field independently of whether they are supplied with current are usually wound around the stator teeth. In order to conduct the magnetic field, the stator is generally of magnetically permeable design, so that the magnetic field is directed in the direction of a rotor of the electrical machine.
In order to make the stator magnetically permeable, it is often formed from stacked electrical laminations. As an alternative, segments of the stator and also complete stators can also be produced with the aid of pulverulent materials. Pulverulent materials are then processed by a finishing method, such as hot-pressing, sintering, MIM and the like for example.
When producing the stators which are provided with stator coils, a compromise has to be found between the ability to produce said stators in a simple manner and good magnetic permeability. The ability to produce said stators is defined, in particular, by the accessibility to slots, that is to say the ability to wind the individual stator teeth or to introduce winding sides between two adjacent stator teeth, and a low level of expenditure on assembly.
For example, accessibility to slots which is good in relation to a full section and good magnetic permeability can be achieved by the stator being constructed with the aid of segment elements or individual segments which have to be joined to form the stator after the stator teeth have been wound. One example of a production method of this kind is that for T-segment stators. However, the joining process is associated with considerable additional expenditure in relation to a non-segmented stator body in this case.
Secondly, as disclosed in document DE 198 42 948, design solutions are available which increase the expenditure on assembly in relation to the full section to an only insignificant extent, but, on account of their structural form, can be constructed only with a system-related magnetic short circuit. As a result, these solutions have a disadvantage in respect of efficiency in relation to full-section or T-segment stators. In particular, provision is made for the stator to be constructed with tooth heads, which are connected to one another, of stator teeth, wherein the tooth heads are connected to one another by means of webs of reduced cross section.
Document DE 10 2005 004 565 discloses a method for constructing a stator with a two-state steel with a high relative permeability. In order to achieve a low magnetic permeability (low relative permeability) between the tooth heads of adjacent stator teeth, provision is made to subject webs by which the tooth heads are connected to one another to a heat treatment, so that sections with a low relative permeability are produced there. As a result, the magnetic permeability in these sections is considerably reduced.
Document U.S. Pat. No. 5,684,352 discloses rotor designs which have ferromagnetic zones of the stator for flux guidance and magnetically impermeable zones of the stator for flux separation, so that a stray magnetic flux is reduced. The magnetically impermeable zones in the stator are formed, for example, by melting the stator material and by adding austenite-forming elements to the melt.
The object of the present invention is to provide a method for producing a machine component for an electrical machine which can be produced in a simple manner and has good properties in respect of magnetic flux guidance.